Today | Weather | Tuesday, October 21, 2025

Weather in Castle Rock, Colorado

10:34 PM

Now

45° F

Feels Like 41°

Precipitation 0 %

Wind 6 mph

Humidity 35 %

Today

Day 72°

Night 36°

Precipitation 0 %

Wind 6 mph

Castle Rock Weather Forecast Updated

37 minutes ago

Last updated on October 21, 2025 9:56 PM

Weather Forecast History

Last Year's Weather on This Day (October 21, 2024)

Day

66°

Night

45°

Air Quality in Castle Rock

NOW

28 AQI

Good air quality Dominant pollutant: O₃

Pollutant Concentrations:

PM_2.5 1.47 µg/m³

PM₁₀ 1.97 µg/m³

O₃ 0.030 ppm

NO₂ 2 ppb

SO₂ 0 ppb

CO 0.10 ppm

NH₃ 0.88 µg/m³

NO 0 µg/m³

PM_2.5 – Fine particles <2.5μm

PM₁₀ – Inhalable particles <10μm

O₃ – Ozone

NO₂ – Nitrogen dioxide

SO₂ – Sulfur dioxide

CO – Carbon monoxide

NH₃ – Ammonia

NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)

PM_2.5 – 1.47 µg/m³

PM₁₀ – 1.97 µg/m³

O₃ – 58.46 µg/m³

NO₂ – 3.83 µg/m³

SO₂ – 0.08 µg/m³

CO – 110.45 µg/m³

NH₃ – 0.88 µg/m³

NO – 0 µg/m³

View Hourly Air Quality Forecast